IDK about the problem you are experiencing, but to remove the fender you need to remove the fender liner first. To do that, put the car on a jack stand and remove the wheel.
You'll need a torx bit (t-25? 20?) to get those liner fasteners. Then remove the bumper cover. You'll need larger torx bits for that. There's 5 around the center grille, and 2 hidden ones you can get to through the lower bumper vents - the side ones not the center one. And you'll need to remove the 4 fender liner fasters along the front lower edge of the other (passenger) side also. Don't forget to remove the marker lights and unplug them. After all the torx bolts and fender liner fasteners are off, the bumper cover will pull straight forward and off the car.
Now the bumper cover is off - you should be able to remove the plastic bracket that is at the seam where the bumper cover and the fender meet. Once removed, you will be able to access the bolts holding the fender there. There are the bolts just inside the hood along the top of the fender, and then there's 3 (or 4?) bolts on the back edge of the fender inside the wheel well. The 2 lower ones (or is it 3?) will be coated in a body sealant that is like caulking for cars. You will just have to dig through it with a sharp screwdriver, utility knife, or other suitable tool to get to the bolt heads and clean them sufficiently to move the bolt. That sealant will likely also be all along the rear seam of the fender also. Be careful peeling it off as you don't want to scratch/cut through it to expose the underlying metal to corrosion, and you don't want to bend the fender.
A blow dryer on high may help to soften the sealant when you are trying to get that rear edge off. I haven't tried this myself, but it sounds like it might help.
The bonus from this is that you'll know if the fender has been replaced before - it will be easy to remove the bolts and the rear edge won't be glued down if that has happened. And you'll get to see how much mud/dirt/sand/pine needles/maple seeds have accumulated between the fender liner and the fender.
The last thing I'll mention here is that most of the door sagging problems I've seen are on 2 door Golfs, and they are usually cured by prying up on the door rather than trying to adjust the hinges. Call us lazy, but maybe after trying to get the fender off for yourself you'll see why the door gets pried rather than the hinges adjusted. The last time I did this I used a 2x4 along the bottom of the door just inside the outer skin, and put a jack under it to do the lifting while the door was open about 1 foot at the trailing edge.
HTH, Cheers!
PH
